Nick Gordon, Bobbi Kristina Brown's longtime boyfriend whom she often referred to as her "husband," is being accused of causing Brown's death.

An amendment to an existing lawsuit filed against Gordon by Brown's court-appointed conservator, Bedelia Hargrove, claims that Gordon gave Brown a "toxic cocktail" of drugs and then put her face-down in a tub of cold water. All of this allegedly led to Brown suffering significant brain damage and her eventual death.

The original wrongful-death lawsuit was filed on June 24 in Fulton County Superior Court, claiming Gordon took money from her without authorization and abused her physically and emotionally. The amendment was filed Friday (Aug. 7), raising the stakes by including a detailed scene of abuse.

The amended complaint alleges that around 6 a.m. on Jan. 31, Gordon returned to their Atlanta-area home after "being out all-night on a cocaine and drinking binge" and proceeded to review camera footage of Brown and listen to her conversations. The couple began arguing, moving around the house, as Gordon reportedly accused Brown of cheating, while calling her names. This lasted about 30 minutes before "everything abruptly became quiet," the lawsuit alleges.

The suit says then Gordon "gave Bobbi Kristina a toxic cocktail rendering her unconscious and then put her face-down in a tub of cold water causing her to suffer brain damage."

Gordon then came out of the master bedroom wearing a different set of clothes from what he'd been wearing before the argument, got in bed and laid his head on a female guest's ankle and told her, "Now I want a pretty white girl like you," the new amendment continues.

About 15 minutes later, a guest went into the master bedroom to check on Brown and found her unconscious in the bathtub. Oddly, a dustpan was at the bottom of the tub. "Bobby Kristina was unresponsive, unconscious, her mouth was swollen, and another tooth was hanging loosely from her mouth," the suit claims.

It continues, Gordon joined them in the master bedroom and the first thing he did was let the water out, then shouting, "Clean up, clean up." After others began trying to give Brown mouth-to-mouth resuscitation, Gordon allegedly slapped Brown, telling her to "wake up" while trying CPR between slaps. Eventually medical personnel arrived at the scene and Gordon was transported to a hospital where she was revived and later placed into a medically induced coma.

There are further allegations against Gordon as well. Those include further incidents of abuse, such as one days before Jan. 31 where it's claimed Gordon hit Brown in the face so hard it broke the couch she was sitting on, knocking her to the floor, as he proceeded to attack her and kick her until she was bloody, screaming in the fetal position. Brown's tooth was knocked out in this incident.

The report goes on to claim Gordon demanded Brown go upstairs and when she could not walk there herself, he "dragged her upstairs by her hair and threw her in the master bedroom, leaving blood on the walls of the staircase.

After this, Gordon allegedly told to the people present, "I don't do this often."

It also repeats the past claims that Gordon accessed Brown's bank account, while she was in a coma, and took more than $11 million without authorization.

Brown died on July 26 at the age of 22, following nearly six months of hospitalization. She was the only child of the late Whitney Houston and Bobby Brown.

Among the criminal counts listed against Gordon, the lawsuit accuses Gordon assault, battery, intentional infliction of emotional distress, conversion, wrongful death and pain and suffering, seeking at least $10 million. See the full suit here via local NBC affiliate WXIA.

At this time, no criminal charges have been filed against Gordon. Any testimony given by Gordon in this civil suit could later be used in a criminal case.